Evidence for genetic distinction among sympatric ecotypes of Arctic char (Salvelinus alpinus) in south‐western Alaskan lakes

Resource polymorphism may play an important role in the process of speciation. The Arctic char (Salvelinus alpinus) exhibits great phenotypic and genetic diversity across its range, making it an ideal species for studies of resource polymorphism and divergence. Here, we investigated genetic variation at 11 microsatellite loci among 287 Arctic char from five isolated yet proximate postglacial lakes in south‐western Alaska that were previously examined for resource polymorphism. Significant differences in pairwise F_ST were detected among all lakes (range from 0.05 to 0.28, all P < 0.02). In one lake (Lower Tazimina Lake), we found evidence for two genetic groups of char and for significant differences in the distribution of microsatellite variability among at least two of the three previously described body size morphotypes (‘large’‐, ‘medium’‐, and ‘small’‐bodied char; maximum F_ST = 0.09; differences in admixture proportions). We also found a significant association between genetic admixture proportions and gill raker counts among body size morphs (r = ?0.73, P < 0.001). Our data represent the first record of genetically distinct sympatric morphs of Arctic char in Alaska and provide further evidence that differences in morphology associated with feeding (gill rakers) and growth trajectories reflect niche diversification and promote genetic divergence in Holarctic populations of Arctic char.     

马蔺的花部构造及开花授粉生物学特性

对马蔺的花部特征、开花动态、授粉特性及传粉媒介等进行了研究,运用多种处理方式,对马蔺的传粉机制进行测定。结果表明:自然条件下,马蔺5～6月开花,群体花期约40d,盛花期约25d,单花花期约58h。马蔺的繁育系统属于异交,部分自交亲和,自然传粉需要借助传粉媒介,虫媒传粉是其传粉方式之一。     

利用Wood模型拟合中国荷斯坦牛乳脂率变化的效果分析

为了解中国荷斯坦牛乳脂率变化规律,本文利用Wood模型对我国南方5个大中型奶牛场2008~2010年1~3胎中国荷斯坦牛33 194条测定日乳脂率进行曲线拟合。结果表明:中国荷斯坦牛乳脂率变化曲线为典型的倒抛物线形,第一胎拟合度最高(0.9820),第三胎最低(0.9789)。二胎牛乳脂率最先达到最低点(第16周),而三胎乳脂率最后达到(第19周)。就最低乳脂率而言,二胎牛最大(3.54%),而三胎牛最小(3.45%)。综合各方面情况得出,Wood模型适用于中国荷斯坦牛乳脂率变化的曲线拟合。     

Single layer centrifugation of stallion spermatozoa consistently selects the most robust spermatozoa from the rest of the ejaculate in a large sample size

Reasons for performing study: An improvement in sperm quality after single layer centrifugation (SLC) has been seen in previous studies using small sample sizes (for example, n = 10 stallions). There is a need to investigate whether this improvement is repeatable over several breeding seasons with a larger number of stallions (n ≥ 30 stallions). Objective: To make a retrospective analysis of the results of SLC performed on more than 250 sperm samples (176 ejaculates) from 31 stallions in 3 consecutive breeding seasons. Methods: Sperm quality (motility, proportion of morphologically normal spermatozoa and the proportion of spermatozoa with undamaged chromatin) was assessed before and after SLC. Results: All parameters of sperm quality examined were significantly better in sperm samples after SLC than in their unselected counterparts (P<0.001 for each parameter). The yield of spermatozoa obtained after SLC was influenced by the type of extender used and also by the concentration of spermatozoa in the original ejaculate, with fewer spermatozoa being recovered when the loading dose contained a high concentration of spermatozoa. The optimal concentration was approximately 100 × 10⁶/ml. Sperm concentration in the samples loaded on to the colloid influenced the sperm yield while the type of semen extender affected sperm quality and survival. Furthermore, the scaled‐up SLC method was found to be suitable for use with a range of ejaculates, with similar sperm kinematics being observed for standard and scaled‐up preparations. Conclusions: SLC consistently improved the quality of stallion sperm samples from a large number of ejaculates. The method could be scaled‐up, allowing larger volumes of ejaculate to be processed easily from a wide range of stallions.     

The Alleviating Effect of Elevated CO2 on Heat Stress Susceptibility of Two Wheat (Triticum aestivum L.) Cultivars

This study analysed the alleviating effect of elevated CO₂ on stress‐induced decreases in photosynthesis and changes in carbohydrate metabolism in two wheat cultivars (Triticum aestivum L.) of different origin. The plants were grown in ambient (400 μl l^?1) and elevated (800 μl l^?1) CO₂ with a day/night temperature of 15/10 °C. At the growth stages of tillering, booting and anthesis, the plants were subjected to heat stress of 40 °C for three continuous days. Photosynthetic parameters, maximum quantum efficiency of photosystem II (PSII) photochemistry (F_v/F_m) and contents of pigments and carbohydrates in leaves were analysed before and during the stress treatments as well as after 1 day of recovery. Heat stress reduced P_N and F_v/F_m in both wheat cultivars, but plants grown in elevated CO₂ maintained higher P_N and F_v/F_m in comparison with plants grown in ambient CO₂. Heat stress reduced leaf chlorophyll contents and increased leaf sucrose contents in both cultivars grown at ambient and elevated CO₂. The content of hexoses in the leaves increased mainly in the tolerant cultivar in response to the combination of elevated CO₂ and heat stress. The results show that heat stress tolerance in wheat is related to cultivar origin, the phenological stage of the plants and can be alleviated by elevated CO₂. This confirms the complex interrelation between environmental factors and genotypic traits that influence crop performance under various climatic stresses.     

Overload of ferric ammonium citrate triggers MAPK pathways by producing high level of reactive oxygen species and induces apoptosis of human hFOB1.19 osteoblast cells

AIM：To investigate the role of reative oxygen species (ROS) generated by iron overload in activating the mitogen-activated protein kinase (MAPK) pathways and apoptosis. METHODS：Cultured human osteoblast cell line hFOB1.19 was treated with ferric ammonium citrate (FAC) at concentrations of 0~500 μmoL/L. The proliferation of hFOB1.19 cells was analyzed by MTT assay. Apoptosis was detected by flow cytometry with Annexin V/PI staining. The expression levels of p-ERK, p-JNK and p-p38 were determined by Western blotting 24 h after treatment with FAC. RESULTS：After treated with FAC, the cell proliferation was inhibited. The early apoptosis and total cell death were significantly increased. The levels of ROS were increased to (35.73±2.52)%, (62.89±4.24)% and (76.06±3.55)% with the increasing doses of FAC treatmen,respectively. The expression levels of p-ERK, p-JNK and p-p38 were also remarkably elevated in FAC groups. CONCLUSION：Iron overload increases intracellular ROS level, thus triggering the MAPK pathways and inducing apoptosis of human hFOB1.19 osteoblast cells.     

Variation of Color and Ray Pattern in Juvenile Shells in Hatchery‐produced Freshwater Triangle Pearl Mussels,Hyriopsis cumingii,in China

The variation and inheritance of juvenile shell color and pigmentation pattern in the freshwater mussel, Hyriopsis cumingii, were reported in 1‐yr‐old progeny of eight families. There were three distinctive phenotypes of shell color and pigmentation patterns observed, including a greenish‐brown shell with radial rays, yellowish‐brown shell with radial rays, and yellowish‐brown shell without radial rays. There were no greenish‐brown individuals without radial rays. The shell color phenotypes showed variation with the growth in juvenile Stage I (1–3 cm in shell length), and the percentage of individuals with radial rays increased once they reached a shell length of 11 mm and then stabilized after reaching 20 mm in shell length. Shell color differentiation became more apparent at a shell length of 26 mm. Results of chi‐square tests of the segregation ratio of shell color or ray phenotypes obtained from eight families at juvenile Stage II (6–9 cm in shell length) suggested that greenish‐brown is controlled by a dominant allele (G) and yellowish‐brown‐shell phenotype is by a recessive allele (y); the ray pattern phenotype is controlled by a recessive (r) and a dominant allele (R) at a single locus. Shell color phenotypes may be a useful genetic marker for future selective breeding of triangle pearl mussels.     

Comparison of nuclear and capacitance‐based soil water measuring techniques in salt‐affected soils

A field calibration experiment was carried out on salt‐affected clayey soil in Syria, to compare the sensitivity to soil electrical conductivity (ECe), and bulk density (ρ_b) of two instruments for estimating soil moisture: the neutron probe (NP) and the Diviner 2000 capacitance probe (CP). The results showed that the values of the correlation coefficient of the calibration were decreased when the ECe and ρ_b values increased; this decrease was more pronounced for the Diviner 2000, indicating that it was more sensitive to ρ_b and ECe than the NP. When only scaled frequency was used in the fitted equation, the Diviner 2000 in wet soil underestimated soil water content significantly at all depths, but especially in the top layer, by up to 0.09 cm³/cm³ compared with gravimetric determinations. However, in dry soil, the Diviner 2000 overestimated the volumetric water content by up to 0.05 cm³/cm³ in the top 15 cm, and by 0.03 cm³/cm³ at 30‐45 cm depth. The performance of the neutron probe was better overall; using a factory calibration curve no significant differences were observed between NP estimates and the gravimetric values. Including both ρ_b and ECe in the calibration equations improved the fits, although the regression coefficient (R²) for the Diviner 2000 remained low.     

弥渡县木材经营加工业现状调查及发展浅析

通过对弥渡县弥城木材市场和新街十字路木材加工厂的木材经营、加工情况进行调查,从而对弥渡县木材经营加工业现状进行了综合评价,并根据目前状况,对今后弥渡县木材经营加工业的发展作些分析,提出合理化建议.